1. Field of the Invention
The present invention relates to pneumatic control devices, such as, for example, air valves, for controlling pressurization of electronic equipment enclosures. More particularly, the present invention relates to a pressurization control device for controlling positive pressurization of an electronic equipment enclosure, such as, for example, a telecommunications equipment enclosure, wherein the device combines and integrates a number of valves or other control components and functions into a single, common valve body or manifold providing a single, shared penetration point into the enclosure, thereby advantageously minimizing the number of penetrations into and potential leakage points from the enclosure.
2. Description of the Prior Art
It is often desirable to provide an enclosure for locating, operationally supporting, and protectively housing electronic equipment. Signal repeater cards, for example, and other electronic equipment used by telecommunication service providers are typically housed in enclosures that are mounted high on telephone poles, underground in manholes, or in other similarly hostile environments. A typical telecommunication equipment enclosure broadly comprises a body operable to receive the equipment; a removable lid operable to cooperate with the body to substantially enclose the equipment while providing access thereto; and a mounting mechanism for securely locating and orienting the enclosure in its proper operating position.
It will be appreciated that the enclosure must protect the electronic equipment from a variety of potentially damaging environmental hazards, including, for example, sun, rain, flooding, snow, and dust and other particulate matter. One well-known way of accomplishing such protection is to seal and positively pressurize the enclosure to minimize or substantially prevent intrusion of potentially damaging moisture and dust or other particulate matter into the enclosure. Such positive pressurization is commonly accomplished by introducing compressed air, nitrogen, or a similar gas into the enclosure. In telecommunication applications, for example, compressed air is typically produced by a compressor at a central office and sent through a main cable trunk, through a cable stub spliced into the main cable trunk, and into the enclosure.
To control the pressurization process and maintain an optimum pressure, the enclosure is typically provided with a number of valves or other pneumatic control components, including, for example, a pressure cutoff valve (PCV) to control the flow of gas into the enclosure; a pressure relief valve (PRV) to prevent over-pressurization; a static pressure valve to allow for quickly pressurizing the enclosure from a local source, which is useful, for example, when testing the pressure relief valve and testing for leaks. These control components are typically discrete items, with each requiring its own penetration point into the enclosure. Unfortunately, any penetration of the enclosure gives rise to a risk of pressure leakage, so that the aforementioned separately-penetrating control components combine to substantially increase the overall risk of leakage. Such leaks, it will be appreciated, may reduce the enclosure""s internal pressure and allow damaging moisture or dust or other particulate matter to enter, or may require a larger volume and faster flow rate of gas into the enclosure to compensate for the lost air. Furthermore, separately manufacturing and installing the various discrete pneumatic control components can involve substantial costly and labor intensive redundancy.
Due to the above-identified and other limitations of the current art, a need exists for an improved mechanism for providing and controlling pressurization of electronic equipment enclosures.
The present invention solves the above-described and other problems and provides a distinct advance in the art of pneumatic control devices, such as, for example, air valves, for controlling pressurization of electronic equipment enclosures. More particularly, the present invention relates to a pressurization control device for controlling positive pressurization of an electronic equipment enclosure, such as, for example, the telecommunications equipment enclosure described above, wherein the device combines and integrates a number of valves or other control components and functions with a single, common valve body or manifold providing a single, shared penetration point into the enclosure. Such positive pressurization is desirable as it minimizes or substantially prevents moisture, dust and other particulate matter, and other potentially damaging materials from entering the enclosure.
In a preferred embodiment, the device broadly comprises the valve body, and includes a plurality of valves or other control components connected to the valve body, such as, for example, a cable air tube connection fitting; a pressure cutoff valve (PCV); a pressure relief valve (PRV); and a static pressure valve or air stem; an express port; and an on/off valve.
The valve body provides a single, common manifold in which or to which the control components are provided or connected and through which these components can access an interior of the enclosure. Externally, the valve body provides a plurality of connection points, with a separate connection point provided for receiving each of the different control components. Internally, the valve body provides a number of passages leading from the connection points to the single, shared penetration point into the enclosure. The penetration point is a shared passageway or duct which projects into or otherwise aligns with an opening in the enclosure. A large O-ring, gasket, or other mechanism may be included which substantially surrounds the penetration point to minimize or substantially prevent leakage between the valve body and the enclosure.
The cable air tube connection fitting is operable to receive an air tube extending from the cable stub, and to thereby introduce compressed air from the cable stub into the valve body. Inside the valve body, a first passage extends from the connection point for the connection fitting to an inlet port of the PCV.
The PCV is operable to start, stop, and otherwise control the flow of compressed air from the connection fitting into the enclosure. An internal valve is manually actuatable to open and close the inlet port of the PCV. When the inlet port is open, air flows from the cable stub, through the tube, through the connection fitting, through the first passage, through the PCV, through the penetration point passageway, and into the enclosure.
The PRV is operable to prevent over-pressurization of the enclosure by automatically releasing air when the enclosure""s internal pressure exceeds a preestablished maximum pressure. A second passage connects the connection point of the PRV to the penetration point passageway. In one embodiment, the PRV includes an internal spring, the loading on which is caused by and therefore correspond to the internal pressure of the enclosure, and includes a built-in adjustment nut for calibrating the PRV and establishing the aforementioned maximum pressure.
The static pressure valve, or air stem, is operable to allow for manually pressurizing the enclosure using a local air source, which is useful, for example, when testing the PRV and when testing the enclosure for leaks. A third passage connects the connection point of the static pressure valve with the penetration point passageway. In one embodiment, the static pressure valve provides internal threads for coupling with a standard air stem retraction valve, and presents an outer diameter dimensioned to accept a standard air chuck.
The express fitting is operable to allow for quickly pressurizing the enclosure using a direct connection to a portable gas supply, such as, for example, a tank of pressurized nitrogen gas. The connection point of the express fitting connects to an inlet port of the on/off valve. When using the express fitting to pressurize the enclosure, the PCV is placed in an off position to prevent the pressurized gas supplied by the portable gas supply from being lost or forced down the cable stub.
The on/off valve is operable to stop, start, and otherwise control introduction into the enclosure of the gas from the local or portable gas supply via the express fitting.
Thus, it will be appreciated that the pressurization control device of the present invention provides a number of advantages over the prior art, including, for example, that it combines and integrates previously discrete valves and other control components into a single valve body providing a single, shared penetration point into the enclosure, thereby substantially reducing the number of required penetration points and the corresponding potential for leaks. Relatedly, the device reduces to manufacturing costs and installation labor by allowing the various valves and other control components to be pre-installed on the valve body and subsequently installed as a unit on the enclosure.
These and other features of the present invention are more fully described below in the section entitled DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT.